Flexographic printing system with solvent replenishment

Abstract

A flexographic printing system uses a flexographic printing plate to produce printed patterns on a substrate. An ink recirculation system is used to reduce variability in system performance resulting from ink viscosity changes. A recirculation pump moves ink through an ink recirculation line connected to an ink reservoir. A metering pump adds a controlled flow rate of solvent from a solvent replenishment chamber into the ink recirculation line, thereby providing replenished ink. The replenished ink is returned to the ink reservoir through a distribution tube that includes a plurality of supply ports at a plurality of spaced apart locations across a width of the ink reservoir. A control system is used to control the flow rate of solvent provided by the metering pump.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]Reference is made to commonly-assigned, co-pending U.S. patent application Ser. No. ______ (Docket K001695), entitled “Flexographic printing system providing controlled feature characteristics” by James Shifley et al.; and to commonly-assigned, co-pending U.S. patent application Ser. No. ______ (DOCKET K001704), entitled “Controlling line widths in flexographic printing” by James Shifley et al., each of which is herein incorporated by reference.FIELD OF THE INVENTION[0002]This invention pertains to the field of flexographic printing, and more particularly to a solvent replenishment system for controlling the viscosity of ink provided to a flexographic printing plate.BACKGROUND OF THE INVENTION[0003]Flexography is a method of printing or pattern formation that is commonly used for high-volume printing runs. It is typically employed for printing on a variety of soft or easily deformed materials including, but not limited to, paper, paperboa...

AI Technical Summary

Benefits of technology

[0024]This invention has the advantage that variations in the performance of the flexographic printing system are reduced by controlling the viscosity of the ink using an ink replenishment process. In some embodiments, reduced variability of the line widths of printed linear features used in touch screen displays is achieved to increase robustness of the device fabrication process.

[0025]It has the additional advantage that feature characteristics of the printed patterns can be analyzed to control the ink replenishment process.

[0026]It has the further advantage that a distribution tube is used to supply replenished ink across a width of the ink reservoir, thereby providing a more uniform distribution of replenished ink and improving the uniformity of the ink viscosity within the ink reservoir.

Problems solved by technology

As the human body is also an electrical conductor, touching the surface of the screen results in a distortion of the screen's electrostatic field, measurable as a change in capacitance.

This method produces a stronger signal than mutual capacitance, but it is unable to resolve accurately more than one finger, which results in “ghosting”, or misplaced location sensing.

Printing such narrow lines stretches the limits of flexographic printing technology, especially when relatively high viscosity printing inks are used.

In particular, it has been found to be difficult to achieve a desired tolerance of plus or minus one micron in line width tolerance.

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